Trouble Sweating Onto Old Copper

Is there a trick to this? I have no problem sweating new copper but when I have to tie into old copper pipe I have a hard time getting a good joint.

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Re:
Trouble Sweating Onto Old Copper

Quote:

Originally Posted by MinConst

Is there a trick to this? I have no problem sweating new copper but when I have to tie into old copper pipe I have a hard time getting a good joint.

Obviously, with old copper there is more cleaning with sandpaper involved. You must get it clean and shiney and use a good quality flux. If you are tying into an existing system then you might be having a water problem and need to drain the system a little more. Other than that everything is pretty much the same.

Re:
Trouble Sweating Onto Old Copper

Try tinning the joints before you sweat them, by heating the area and appling flux to the heated surface. Then add a little bit of solder and see if it runs completely around the area, clean again with fine steel wool and you are ready to apply the fittings.

Re:
Trouble Sweating Onto Old Copper

I will try the tinning. What I see is that the solder does not flow. I have to heat the ******************** out of the joint and even then it doesn't seal. I guess it might be that I'm not cleaning enough. Thanks for the tips. I will try them.

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Re:
Trouble Sweating Onto Old Copper

If by old copper you mean existing, it could be water still in the lines. That has happened to me several times. It doesn't take much water for it to mess up a joint. Even if it seems dry, heating up the pipe can cause water to appear. I have used the white bread trick several times with great success. Good luck.

Also do you guys use propane or mapp gas? I switched to mapp gas and have had better luck since. Thanks.

Re:
Trouble Sweating Onto Old Copper

Quote:

Originally Posted by MinConst

I will try the tinning. What I see is that the solder does not flow. I have to heat the ******************** out of the joint and even then it doesn't seal. I guess it might be that I'm not cleaning enough. Thanks for the tips. I will try them.

If you're using excessive heat, either it's not cleaned properly or you're getting water. Too much heat wiil also burn the flux and effect the flow. I don't recommend tinning and it certainly isn't as easy as 1 2 3. But, they do make a self tinning flux.

Re:
Trouble Sweating Onto Old Copper

Quote:

Originally Posted by GMW

If by old copper you mean existing, it could be water still in the lines. That has happened to me several times. It doesn't take much water for it to mess up a joint. Even if it seems dry, heating up the pipe can cause water to appear. I have used the white bread trick several times with great success. Good luck.

Also do you guys use propane or mapp gas? I switched to mapp gas and have had better luck since. Thanks.

I use propane. I was introduced into the trade with it by an old timer and never had reason to switch. It comes down to personal preferance. Although, I have noticed a lot of guys apply too much heat when they are using mapp.

Re:
Trouble Sweating Onto Old Copper

I am forth generation in plumbing and heating, for some reason I prefer the Actlyenne gas with a soft flame tip for my small stuff.

We carry very large bottles on our rigs with 50+ feet of hose, for small repairs we also carry MC bottles.

When we are doing large scale work we will switch to turbo, and use the big bottles as its much cheaper than swaping out B tanks.

Having these big bottles also allows us to, if need be just add OX bottle switch lines then we are set to either burn, or braze.

At times this can put us over the edge, like in large copper water main repairs, 3 - 4 in size as they require a lot of heat to complete the joint with us carrying the mix gases we can do these pretty quick.

Re:
Trouble Sweating Onto Old Copper

Quote:

Originally Posted by MinConst

Is there a trick to this? I have no problem sweating new copper but when I have to tie into old copper pipe I have a hard time getting a good joint.

You may have considered this but some H2O in the line makes steam pressure and if it has no release it will push out through the last joint. It took me a few days to learn that as a young bootleg plumber. I noticed the real plumbers didn't spend so much time on a joint and never built up pressure. For a while I always made my last joint a union but now a open valve does the trick.RT

Re:
Trouble Sweating Onto Old Copper

i know this is wacked but water problems in a line can be helped by stuffing some BREAD in the line, fluxing, then sweating (pre sanded of course). you got to pull the areator out of a faucet to get the crap out. i know its one of those old timers/ last resort things

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